Plasma etch method for forming plasma etched silicon layer

ABSTRACT

A method for forming an etched silicon layer. There is first provided a first substrate having formed thereover a first silicon layer. There is then etched the first silicon layer to form an etched first silicon layer while employing a plasma etch method employing a plasma reactor chamber in conjunction with a plasma etchant gas composition which upon plasma activation provides at least one of an active bromine containing etchant species and an active chlorine containing etchant species. Within the plasma etch method: (1) a cleaned plasma reactor chamber is seasoned to provide a seasoned plasma reactor chamber having a seasoning polymer layer formed therein; (2) the first silicon layer is etched to form the etched first silicon layer within the seasoned plasma reactor chamber; and (3) the seasoning polymer layer is cleaned from the seasoned plasma reactor chamber to provide the cleaned plasma reactor chamber after etching the first silicon layer to form the etched first silicon layer within the seasoned plasma reactor chamber, prior to etching a second silicon layer to form an etched second silicon layer formed over a second substrate within the plasma reactor chamber while employing the plasma etch method in accord with (1), (2) and (3).

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates generally to methods for formingetched silicon layers within microelectronic fabrications. Moreparticularly, the present invention relates to plasma etch methods forforming with attenuated plasma etch residue plasma etched silicon layerswithin microelectronic fabrications.

[0003] 2. Description of the Related Art

[0004] Microelectronic fabrications are formed from microelectronicsubstrates over which are formed patterned microelectronic conductorlayers which are separated by microelectronic dielectric layers.

[0005] As microelectronic fabrication integration levels have increasedand microelectronic device and patterned microelectronic conductor layerdimensions have decreased, it has become more common in the art ofmicroelectronic fabrication to employ plasma etch methods for formingetched silicon layers, including but not limited to etchedmonocrystalline silicon layers, etched polycrystalline silicon layersand etched amorphous silicon layers, within microelectronicfabrications.

[0006] Such plasma etch methods often employ plasma etchant gascompositions which upon plasma activation provide active bromine and/orchlorine containing etchant species, such as may be derived, for exampleand without limitation, from etchant gases including but not limited tobromine, hydrogen bromide, chlorine and/or hydrogen chloride. Similarly,such etched silicon layers formed within microelectronic fabricationsmay include, but are not limited to: (1) partially etchedmonocrystalline silicon semiconductor substrate layers having shallowand/or deep isolation and/or capacitive trenches etched therein asemployed within semiconductor integrated circuit microelectronicfabrications, as well as; (2) fully etched and patterned polycrystallinesilicon non-substrate layers which may be employed as: (a) patternedpolysilicon conductor layers within microelectronic fabricationsincluding but not limited to semiconductor integrated circuitmicroelectronic fabrications, as well as; (b) gate electrodes withinfield effect transistors (FETs) employed within semiconductor integratedcircuit microelectronic fabrications.

[0007] Similarly, such etched silicon layers when formed withinmicroelectronic fabrications while employing plasma etch methods whichemploy etchant gas compositions which upon plasma activation provideactive bromine and/or chlorine containing etchant species are oftenformed in the presence of silicon containing dielectric layers, such asbut not limited to silicon oxide dielectric layers, silicon nitridedielectric layers and silicon oxynitride dielectric layers. The siliconcontaining dielectric layers may be formed as plasma etch mask hard maskpatterned silicon containing dielectric layers, or in the alternative assubstrate layers, such as, for example and without limitation, as gatedielectric silicon containing dielectric layers formed beneath gateelectrodes formed within field effect transistors (FETs) employed withinsemiconductor integrated circuit microelectronic fabrications.

[0008] While plasma etch methods for forming etched silicon layers foruse within microelectronic fabrications are thus desirable and commonwithin the art of microelectronic fabrication, plasma etch methods forforming etched silicon layers for use within microelectronicfabrications are nonetheless not entirely without problems in the art ofmicroelectronic fabrication. In that regard, it is known in the art ofmicroelectronic fabrication that: (1) it is often difficult toreproducibly and controllably form while employing plasma etch methodsetched silicon layers with attenuated residue formation (such as but notlimited to attenuated particulate contamination residue formation)within microelectronic fabrications; and (2) in situations where theetched silicon layers are formed in the presence of silicon containingdielectric layers, it is often difficult to reproducibly andcontrollably form the etched silicon layers with enhanced selectivity ofthe plasma etch methods for the etched silicon layers with respect tothe silicon containing dielectric layers.

[0009] It is thus towards the goal of providing for use when fabricatingmicroelectronic fabrications plasma etch methods for reproducibly andcontrollably forming within microelectronic fabrications etched siliconlayers with: (1) attenuated residue formation (such as but not limitedto particulate contamination residue formation); and (2) enhancedselectivity of the plasma etch methods for the etched silicon layerswith respect to silicon containing dielectric layers when those etchedsilicon layers are formed in the presence of silicon containingdielectric layers, that the present invention is directed.

[0010] Various plasma processing methods have been disclosed in the artof microelectronic fabrication for forming plasma processedmicroelectronic layers with desirable properties within microelectronicfabrications.

[0011] For example, Gupta et al., in U.S. Pat. No. 5,456,796, disclosesa plasma processing method for attenuating particulate generation anddeposition upon a substrate employed within a microelectronicfabrication when processing the substrate employed within themicroelectronic fabrication while employing the plasma processingmethod. The plasma processing method employs: (1) a rapid increase of aplasma power within a plasma reactor chamber to a high plasma powerlevel prior to introduction of the substrate into a plasma reactorchamber to thus provide for effective cleaning of the plasma reactorchamber prior to introduction of the substrate into the plasma reactorchamber, in conjunction with; (2) a slower increase of the plasma powerwithin the plasma reactor chamber subsequent to introduction of thesubstrate into the plasma reactor chamber in order to avoid circulationof particles within the plasma reactor chamber which would otherwisesettle upon the substrate.

[0012] In addition, Saito et al., in U.S. Pat. No. 5,681,424, disclose aplasma processing method for cleaning a plasma reactor chamber withinwhich is plasma etched a silicon layer formed over a substrate whileemploying a hydrogen bromide containing etchant gas composition, whilesimultaneously dissipating an electrostatic charge formed upon thesubstrate incident to use within a plasma apparatus employed within theplasma processing method of an electrostatic chuck for securing thesubstrate within the plasma reactor chamber. The plasma processingmethod employs an oxygen containing etchant gas composition forsimultaneously cleaning the reactor chamber and dissipating theelectrostatic charge formed upon the substrate.

[0013] Further, Leung et al., in U.S. Pat. No. 5,705,080, disclose aplasma processing method for cleaning deposits from within a reactorchamber, including but not limited to a plasma reactor chamber, withoutdamaging within the reactor chamber reactor components which areotherwise sensitive to the plasma processing method. The plasmaprocessing method employs covering within the reactor chamber componentswhich are otherwise sensitive to the plasma processing method prior tocleaning the deposits from within the reactor chamber while employingthe plasma processing method.

[0014] Still further, Murugesh et al., in U.S. Pat. No. 5,811,356,disclose a plasma processing method and a plasma processing apparatuswhich provide for a reduced concentration of mobile ions and metalcontaminants within a reactor chamber so that there may be fabricatedwithin the reactor chamber microelectronic layers, particularlymicroelectronic dielectric layers, with enhanced reliability. The methodemploys, when seasoning the reactor chamber while employing the plasmaprocessing method and the plasma processing apparatus, a bias radiofrequency power density of greater than 0.051 watts per squaremillimeter and a seasoning time of greater than about 30 seconds.

[0015] Finally, Gupta, in U.S. Pat. No. 5,824,375, discloses a plasmaprocessing method and a plasma processing apparatus for reducingfluorine and other sorbable contaminants in a plasma reactor chamberemployed within a chemical vapor deposition (CVD) method, such as butnot limited to a plasma enhanced chemical vapor deposition (PECVD)method. The plasma processing method and the plasma processing apparatusemploy an inert plasma treatment of the plasma reactor chamber aftercleaning the plasma reactor chamber while employing a fluorinecontaining plasma etch method and prior to forming within the plasmareactor chamber while employing a plasma deposition method a passivatingseasoning layer within the plasma reactor chamber.

[0016] Desirable in the art of microelectronic fabrication areadditional plasma etch methods and materials which may be employed forreproducibly and controllably forming with attenuated residue etchedsilicon layers within microelectronic fabrications with enhancedselectivity of the plasma etch methods for the etched silicon layerswith respect to silicon containing dielectric layers when the etchedsilicon layers are formed in the presence of silicon containingdielectric layers.

[0017] It is towards the foregoing objects that the present invention isdirected.

SUMMARY OF THE INVENTION

[0018] A first object of the present invention is to provide a plasmaetch method for reproducibly and controllably forming an etched siliconlayer within a microelectronic fabrication.

[0019] A second object of the present invention is to provide a plasmaetch method in accord with the first object of the present invention,where the etched silicon layer is reproducibly and controllably formedwith attenuated residue (such as but not limited to particulatecontamination residue).

[0020] A third object of the present invention is to provide a plasmaetch method in accord with the first object of the present invention andthe second object of the present invention, where the plasma etch methodreproducibly and controllably exhibits enhanced selectivity for theetched silicon layer with respect to a silicon containing dielectriclayer when the etched silicon layer is formed in the presence of thesilicon containing dielectric layer within the microelectronicfabrication.

[0021] A fourth object of the present invention is to provide a methodin accord with the first object of the present invention, the secondobject of the present invention and the third object of the presentinvention, which method is readily commercially implemented.

[0022] In accord with the objects of the present invention, there isprovided a plasma etch method for forming an etched silicon layer. Topractice the method of the present invention, there is first provided afirst substrate having formed thereover a first silicon layer. There isthen etched the first silicon layer to form an etched first siliconlayer while employing a plasma etch method employing a plasma reactorchamber in conjunction with a plasma etchant gas composition which uponplasma activation provides at least one of an active bromine containingetchant species and an active chlorine containing etchant species,wherein within the plasma etch method: (1) a cleaned plasma reactorchamber is seasoned to provide a seasoned plasma reactor chamber havinga seasoning polymer layer formed therein; (2) the first silicon layer isetched to form the etched first silicon layer within the seasoned plasmareactor chamber; and (3) the seasoning polymer layer is cleaned from theseasoned plasma reactor chamber to provide the cleaned plasma reactorchamber after etching the first silicon layer to form the etched firstsilicon layer within the seasoned plasma reactor chamber, prior toetching a second silicon layer to form an etched second silicon layerformed over a second substrate within cleaned plasma reactor chamberwhile employing the plasma etch method in accord with (1), (2) and (3).

[0023] The present invention provides a plasma etch method forreproducibly and controllably forming an etched silicon layer within amicroelectronic fabrication, where the etched silicon layer is formedwith attenuated residue (such as but not limited to particulate residue)and where the plasma etch method exhibits enhanced selectivity for theetched silicon layer with respect to a silicon containing dielectriclayer when the etched silicon layer is formed in the presence of thesilicon containing dielectric layer within the microelectronicfabrication. The present invention realizes the foregoing objects byemploying within the present invention: (1) a cleaned plasma reactorchamber seasoning to provide a seasoned plasma reactor chamber having aseasoning polymer layer formed therein; (2) a single substrate siliconlayer etching within the seasoned plasma reactor chamber; and (3) acleaning of the seasoning polymer layer from the seasoned plasma reactorchamber to provide the cleaned plasma reactor chamber, prior to etchinga second silicon layer to form an etched second silicon layer formedover a second substrate while employing the preceding steps (1), (2) and(3).

[0024] The method of the present invention is readily commerciallyimplemented. The present invention employs an apparatus which isgenerally conventional in the art of microelectronic fabrication. Sinceit is a process control and materials selection which provides at leastin part the present invention, rather than the existence of methods andapparatus which provides the present invention, the method of thepresent invention is readily commercially implemented.

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The objects, features and advantages of the present invention areunderstood within the context of the Description of the PreferredEmbodiment, as set forth below. The Description of the PreferredEmbodiment is understood within the context of the accompanyingdrawings, which form a material part of this disclosure, wherein:

[0026]FIG. 1, FIG. 2, FIG. 3 and FIG. 4 show a series of schematiccross-sectional diagrams of a plasma reactor chamber at progressivestages within a plasma etch method in accord with the present invention.

[0027]FIG. 5 shows a plot of Plasma Reactor Chamber Seasoning PolymerContent versus Number of Substrates Processed, for a series ofsubstrates processed within a plasma reactor chamber in accord with thepresent invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

[0028] The present invention provides a plasma etch method forreproducibly and controllably forming an etched silicon layer within amicroelectronic fabrication, where the etched silicon layer is formedwith attenuated residue (such as but not limited to particulatecontamination residue) and where the plasma etch method exhibitsenhanced selectivity for the etched silicon layer with respect to asilicon containing dielectric layer when the etched silicon layer isformed in the presence of the silicon containing dielectric layer withinthe microelectronic fabrication. The method of the present inventionrealizes the foregoing objects by employing within the plasma etchmethod: (1) a seasoning of a cleaned plasma reactor chamber to form aseasoned plasma reactor chamber having a seasoning polymer layer formedtherein; (2) a single substrate silicon layer etching within theseasoned plasma reactor chamber; and (3) a cleaning of the seasoningpolymer layer from the seasoned plasma reactor chamber to provide thecleaned plasma reactor chamber, prior to etching a second silicon layerto form an etched second silicon layer formed over a second substratewhile employing the preceding steps (1), (2) and (3).

[0029] The plasma etch method of the present invention may be employedfor forming from silicon layers including but not limited tomonocrystalline silicon layers, polycrystalline silicon layers andamorphous silicon layers etched silicon layers including but not limitedto etched monocrystalline silicon layers, etched polycrystalline siliconlayers and etched amorphous silicon layers within microelectronicfabrications including but not limited to integrated circuitmicroelectronic fabrications, ceramic substrate microelectronicfabrications, solar cell optoelectronic microelectronic fabrications,sensor image array optoelectronic microelectronic fabrications anddisplay image array optoelectronic microelectronic fabrications.

[0030] Referring now to FIG. 1 to FIG. 4, there is shown a seriesschematic cross-sectional diagrams illustrating a plasma reactor chamberat progressive stages within a plasma etch method in accord with thepresent invention. Shown in FIG. 1 is a schematic cross-sectionaldiagram of the plasma reactor chamber at an early stage in practice ofthe plasma etch method of the present invention.

[0031] Shown in FIG. 1 is a cleaned plasma reactor chamber 10 havingfabricated therein a platen 12. As is understood by a person skilled inthe art, plasma reactor chambers are available in any of several types,sizes and configurations as are needed and desirable to plasma processany of several types of substrates as are employed within various typesof microelectronic fabrications. Various of such types, sizes andconfigurations of plasma reactor chambers are disclosed within thevarious references cited within the Description of the Related Art, thedisclosures of which references are incorporated herein fully byreference. As is similarly understood by a person skilled in the art,the platen 12 as illustrated within the schematic cross-sectionaldiagram of FIG. 1 is sized appropriately to accommodate a substrateemployed within a microelectronic fabrication which is fabricatedemploying the plasma etch method of the present invention.

[0032] Referring now to FIG. 2, there is shown a schematiccross-sectional diagram illustrating a plasma reactor chamber at afurther stage within the plasma etch method in accord with the presentinvention.

[0033] Shown in FIG. 2 is a plasma reactor chamber otherwise equivalentto the cleaned plasma reactor chamber 10 whose schematic cross-sectionaldiagram is illustrated in FIG. 1, but wherein there is formed uponinterior surfaces of the cleaned plasma reactor chamber 10 a seasoningpolymer layer 14, thus forming from the cleaned plasma reactor chamber10 a seasoned plasma reactor chamber 10′. Within the preferredembodiment of the present invention, the seasoning polymer layer 14 istypically and preferably formed of a seasoning polymer material selectedfrom the group including but not limited to: (1) a silicon and brominecontaining seasoning polymer material; (2) a silicon, bromine and oxygencontaining seasoning polymer material; (3) a silicon and chlorineseasoning polymer material; (4) a silicon, chlorine and oxygencontaining seasoning polymer material; (5) a silicon, bromine andchlorine seasoning polymer material; and (6) a silicon, bromine,chlorine and oxygen seasoning polymer material.

[0034] Within the preferred embodiment of the present invention, theseasoning polymer layer 14 may be formed employing any one of at leastthree seasoning polymer layer formation methods.

[0035] The first of the at least three seasoning polymer layer formationmethods is a dummy wafer seasoning polymer layer formation method whichemploys in the alternative: (1) a silicon oxide coated dummy wafer inconjunction with a seasoning plasma etch method employing at least oneof a bromine containing etchant gas and a chlorine containing etchantgas; (2) a silicon oxide coated dummy wafer in conjunction with aseasoning plasma etch method employing at least one of a brominecontaining etchant gas and a chlorine containing etchant gas, inaddition to an oxygen containing etchant gas; and (3) a silicon dummywafer in conjunction with a seasoning plasma etch method employing atleast one of a bromine containing etchant gas and a chlorine containingetchant gas, in addition to an oxygen containing etchant gas. Within thepreferred embodiment of the present invention, the bromine containingetchant gas is typically and preferably selected from the groupconsisting of hydrogen bromide and bromine, while the chlorinecontaining etchant gas is typically and preferably selected from thegroup consisting of hydrogen chloride and chlorine. Similarly, withinthe preferred embodiment of the present invention, the oxygen containingetchant gas is typically and preferably selected from the groupconsisting of oxygen, ozone, nitrous oxide and nitric oxide. Mosttypically and preferably, the bromine containing etchant gas is hydrogenbromide, the chlorine containing etchant gas is chlorine or hydrogenchloride and the oxygen containing etchant gas is oxygen.

[0036] Typically and preferably, the dummy wafer seasoning method willemploy when forming the seasoning polymer layer 14 within a seasonedplasma reactor chamber 10′ employed for plasma processing an eight inchdiameter substrate: (1) a plasma reactor chamber 10 pressure of fromabout 1 to about 500 mtorr; (2) a source radio frequency power of fromabout 10 to about 2000 watts at a source radio frequency of from 2 MHZto 13.56 MHZ, and an external bias power of up to about 500 watts; (3) aplasma reactor chamber 10 temperature and a dummy wafer temperature offrom about 20 to about 200 degrees centigrade; (4) a bromine and/orchlorine containing etchant gas flow rate of from about 10 to about 200standard cubic centimeters per minute (sccm); (5) an oxygen containingetchant gas flow rate of from about 1 to about 50 standard cubiccentimeters per minute (sccm); (6) a backside cooling gas, typically andpreferably but not exclusively helium, at a pressure of from about 1 toabout 50 torr and a flowrate of from about 2 to about 50 standard cubiccentimeters per minute (sccm); (7) a magnetic field of up to about 200gauss; and (8) a plasma seasoning time of from about 5 to about 120seconds.

[0037] The second of the at least three seasoning polymer layerformation methods is an in-situ seasoning polymer layer formation methodwherein a product substrate having formed exposed thereover a siliconlayer, or a silicon layer in the presence of a silicon containingdielectric layer, such as but not limited to a silicon oxide dielectriclayer, a silicon nitride dielectric layer or a silicon oxynitridedielectric layer, is plasma etched at a comparatively lower plasma powerand a comparatively higher reactor chamber pressure to form theseasoning polymer layer 14 within the seasoned reactor chamber 10′ whilenot damaging the product substrate. Under such circumstances whenemploying an in-situ seasoning method, there is employed: (1) a siliconcontaining seasoning polymer layer forming gas; (2) at least one of abromine containing seasoning polymer layer forming gas and a chlorinecontaining seasoning polymer layer forming gas; and (3) an optionaloxygen containing seasoning polymer layer forming gas, where the lattertwo seasoning polymer layer forming gases are provided in accord withchoices for the bromine and/or chlorine containing etchant gas and theoxygen containing etchant gas as disclosed above as employed within thedummy wafer seasoning polymer layer formation method. The siliconcontaining seasoning polymer layer forming gas may be selected from thegroup including but not limited to silicon bromide (which may also serveas a bromine containing seasoning polymer layer forming gas), silicontetrachloride (which may also serve as a chlorine containing seasoningpolymer layer forming gas) and silane.

[0038] Typically and preferably, the in-situ seasoning polymer layerforming method will employ when forming the seasoning polymer layer 14within a seasoned plasma reactor chamber 10′ employed for plasmaprocessing an eight inch diameter substrate: (1) a plasma reactorchamber pressure of from about 50 to about 1000 mtorr; (2) a radiofrequency source power of from about 10 to about 1000 watts at a sourceradio frequency of from 2 MHZ to 13.56 MHZ, without an external biassource; (3) a plasma reactor chamber 10 and product substratetemperature of from about 20 to about 200 degrees centigrade; (4) asilicon containing seasoning polymer layer forming gas flow rate of fromabout 1 to about 200 standard cubic centimeters per minute (sccm); (5) abromine and/or chlorine containing seasoning polymer layer forming gasflow rate of from about 10 to about 200 standard cubic centimeters perminute (sccm); (6) an optional oxygen containing seasoning polymer layerforming gas flow rate of from about 1 to about 50 standard cubiccentimeters per minute (sccm); (7) a backside cooling gas, typically andpreferably but not exclusively helium, at a pressure of from about 1 toabout 50 torr and a flowrate of from about 2 to about 50 standard cubiccentimeters per minute (sccm); (8) a magnetic field of up to about 200gauss; and (9) a plasma seasoning time of from about 5 to about 120seconds.

[0039] Finally, within the preferred embodiment of the present inventionthe third of the at least three seasoning polymer layer forming methodsis a waferless seasoning polymer layer forming method which employs aseasoning polymer layer forming gas composition employing depositionparameters and limits as employed for the in-situ seasoning polymerlayer forming method, as above, but without the presence of the productsubstrate, or any other substrate, within the cleaned plasma reactorchamber 10.

[0040] Within the preferred embodiment of the present invention theremay additionally be employed within any of the foregoing three seasoningpolymer layer forming methods an optional fluorine containing etchantgas/seasoning gas, such as but not limited to a nitrogen trifluoridefluorine containing etchant gas/seasoning gas or a sulfur hexafluoridefluorine containing etchant gas/seasoning gas, but not a fluorocarboncontaining etchant gas/seasoning gas, at a flow rate of from about 1 toabout 100 standard cubic centimeters per minute, more preferably fromabout 1 to about 20 standard cubic centimeters per minute (sccm).Similarly, and in particular with respect to the waterless seasoningpolymer layer forming method, it may also be desirable within thepresent invention to employ within the cleaned plasma reactor chamber 10a ceramic chuck, rather than a polyimide coated chuck, in order to avoidattack of a polyimide layer formed upon the polyimide coated chuck bythe plasma seasoning polymer layer forming methods.

[0041] Referring now to FIG. 3, there is shown a schematiccross-sectional diagram illustrating a plasma reactor chamber at afurther stage in the plasma etch method in accord with the presentinvention.

[0042] Shown in FIG. 3 is a plasma reactor chamber otherwise equivalentto the seasoned plasma reactor chamber 10′ as illustrated within theschematic cross-sectional diagram of FIG. 2, but wherein there ispositioned upon the platen 12 a substrate 16 which is etched within asilicon layer etch plasma 18 which simultaneously supplements theseasoning polymer layer 14 to form a supplemented seasoning polymerlayer 14′ within a supplementally seasoned plasma reactor chamber 10″.

[0043] Although not specifically illustrated within the schematiccross-sectional diagram of FIG. 3, the substrate 16 has formed thereovera silicon layer which is etched to form an etched silicon layer withinthe silicon layer etch plasma 18. The silicon layer may be formed from asilicon material selected from the group consisting of monocrystallinesilicon materials, polycrystalline silicon materials and amorphoussilicon materials. Typically and preferably, although not exclusively,the silicon layer will be masked with a mask layer which may be formedfrom a silicon containing hard mask dielectric material, such as but notlimited to a silicon oxide hard mask dielectric material, a siliconnitride hard mask dielectric material or a silicon oxynitride hard maskdielectric material, or in the alternative a photoresist mask material,although photoresist mask materials are not preferred since they mayeither add carbon to the supplemented seasoning polymer layer 14′, or inthe alternative add various contaminants to the substrate 16. Similarly,the silicon layer will often be formed in the presence of a siliconcontaining dielectric layer, which if not employed for forming the hardmask layer may otherwise be in contact with the silicon layer, such as,for example and without limitation as formed immediately beneath thesilicon layer.

[0044] Within the preferred embodiment of the present invention withrespect to the silicon layer etch plasma 18, the silicon layer etchplasma 18 typically and preferably employs an etchant gas compositionwhich upon plasma activation forms at least one of an active brominecontaining etchant species and an active chlorine containing etchantspecies (such as may be formed from an etchant gas including but notlimited to hydrogen bromide, bromine, hydrogen chloride and/orchlorine), along with an optional oxygen containing etchant species(such as but not limited to oxygen, ozone, nitrous oxide or nitricoxide) and an optional fluorine containing etchant species (such as butnot limited to nitrogen trifluoride and sulfur hexafluoride). Morepreferably, the silicon layer etch plasma 18 employs an etchant gascomposition comprising hydrogen bromide, oxygen and nitrogentrifluoride.

[0045] When etching a silicon layer to form an etched silicon layer overan eight inch diameter substrate 16 within the supplementally seasonedplasma reactor chamber 10″ as illustrated within the schematiccross-sectional diagram of FIG. 3, the silicon layer etch plasma 18 alsoemploys: (1) a reactor chamber pressure of from about 1 to about 500mtorr; (2) a radio frequency source power of from about 10 to about 2000watts at a source radio frequency of from 2 MHz to 13.56 MHz and anexternal bias power of up to about 500 watts; (3) a substrate 16 andsupplementally seasoned plasma reactor chamber 10″ temperature of fromabout 20 to about 200 degrees centigrade; (4) a hydrogen bromide flowrate of from about 10 to about 200 standard cubic centimeters per minute(sccm); (5) an oxygen flow rate of from about 1 to about 50 standardcubic centimeters per minute (sccm); (6) a nitrogen trifluoride flowrate of from about 1 to about 50 standard cubic centimeters per minute(sccm); (7) a backside cooling gas, typically and preferably but notexclusively helium, at a pressure of from about 1 to about 50 torr and aflowrate of from about 2 to about 50 standard cubic centimeters perminute (sccm); and (8) a magnetic field of up to about 200 gauss.

[0046] Referring now to FIG. 4, there is shown a schematiccross-sectional diagram illustrating a plasma reactor chamber at afurther stage within the plasma etch method in accord with the presentinvention.

[0047] Shown in FIG. 4 is a schematic cross-sectional diagram of aplasma reactor chamber otherwise equivalent to the supplementallyseasoned plasma reactor chamber 10″ whose schematic cross-sectionaldiagram is illustrated in FIG. 3, but wherein the plasma reactor chamberhas been cleaned of the supplemented seasoning polymer layer 14′ andreturned to a condition equivalent, although not necessarily identical,to the condition of the cleaned plasma reactor chamber 10 as illustratedwithin the schematic cross-sectional diagram of FIG. 1.

[0048] To thus strip from within the supplementally seasoned plasmareactor chamber 10″ as illustrated within the schematic cross-sectionaldiagram of FIG. 3 the supplemented seasoning polymer layer 14′ toprovide the cleaned plasma reactor chamber 10 whose schematiccross-sectional diagram is illustrated in FIG. 4 and FIG. 1, there istypically and preferably employed a plasma stripping method, typicallyand preferably employing an etchant gas composition which upon plasmaactivation provides an active fluorine containing etchant species. Moretypically and preferably, the etchant gas composition employs at leastone of nitrogen trifluoride and sulfur hexafluoride, and preferably nota fluorocarbon etchant gas.

[0049] When stripping the supplemented seasoning polymer layer 14′ fromwithin the supplementally seasoned plasma reactor chamber 10″ which isemployed in processing an eight inch diameter substrate 16, the plasmastripping method also employs: (1) a supplementally seasoned plasmareactor chamber 10″ pressure of from about 50 to about 500 mtorr; (2) asource radio frequency of from about 100 to about 2000 watts at a sourceradio frequency of 2 MHZ to 13.56 MHZ, and a bias power of up to about500 watts; (3) a supplementally seasoned plasma reactor chamber 10″temperature of from about 20 to about 200 degrees centigrade; (4) anitrogen trifluoride or a sulfur hexafluoride flow rate of from about 10to about 500 standard cubic centimeters per minute (sccm); (5) abackside cooling gas, typically and preferably but not exclusivelyhelium, at a pressure of from about 1 to about 50 torr and a flowrate offrom about 2 to about 50 standard cubic centimeters per minute (sccm);and (6) a magnetic field of up to about 200 gauss.

[0050] Although not specifically illustrated within the schematiccross-sectional diagram of FIG. 4, the plasma stripping method may alsooptionally employ a dummy wafer. Similarly, and in particular when adummy wafer is not employed within the plasma stripping method, it mayalso be desirable within the present invention to employ within thesupplementally seasoned plasma reactor chamber 10″ a ceramic chuck,rather than a polyimide coated chuck, in order to avoid attack of apolyimide layer formed upon the polyimide coated chuck by the plasmastripping method.

[0051] Upon stripping from the supplementally seasoned plasma reactorchamber 10″ the supplemented seasoning polymer layer 14′ as illustratedwithin the schematic cross-sectional diagram of FIG. 3 to provide thecleaned reactor chamber 10 as illustrated within the schematiccross-sectional diagram of FIG. 4, there is provided a cleaned reactorchamber within which may be processed a second substrate in accord witha process flow in accord with FIG. 1, FIG. 2 and FIG. 3, where thesecond substrate has formed thereover a second silicon layer which isetched to form an etched second silicon layer.

[0052] By employing within the method of the present invention a plasmareactor chamber seasoning, a silicon layer etching and a plasma reactorchamber cleaning for each single substrate fabricated within the plasmareactor chambers as illustrated within the schematic cross-sectionaldiagrams of FIG. 1 to FIG. 4, there is reproducibly and controllablyprovided with an enhanced uniformity an etched silicon layer formed overthe substrate 16, where the etched silicon layer is reproducibly andcontrollably formed with an attenuated residue (such as particulatecontamination residue) formed upon the etched silicon layer formed overthe substrate 16 and an attenuated etching of a silicon containingdielectric layer formed in the presence of the etched silicon layer.

[0053] Referring now to FIG. 5, there is shown a graph of Plasma ReactorChamber Seasoning Polymer Content versus Number of Substrates Processedfor a plasma reactor chamber in accord with the preferred embodiment ofthe present invention. As is illustrated by the legend which accompaniesFIG. 5, there is shown within FIG. 5 by means of the dashed upwardlypointing arrows a portion of the process of the present invention whichis directed towards forming the seasoning polymer layer within theseasoned plasma reactor chamber. Similarly, in conjunction with theseasoning polymer layer there is shown by addition of the solid upwardlypointing arrows the supplemented seasoning polymer layer content withinthe supplementally seasoned reactor chamber. Finally, there is shown bythe downwardly pointed arrows the results of cleaning the reactorchamber of the present invention to remove therefrom the supplementedseasoning polymer layer.

[0054] As is similarly also illustrated within the graph of FIG. 5 thereis a shaded target range for seasoning polymer content within which itis desired to operate the plasma reactor chamber while employing themethod of the present invention. Above the shaded range of seasoningpolymer content the thickness of seasoning polymer layer becomessufficiently thick such that it is believed that flaking occurs andcontributes to particulate contamination upon a substrate over which isformed a silicon layer which is etched within the plasma reactorchamber. Similarly, under conditions where the seasoning polymer layeris formed within the plasma reactor chamber of a content less than aminimal requisite content, there is observed a loss in selectivity foretching of the silicon layer formed over the substrate with respect to asilicon containing dielectric layer also formed over the substrate.

[0055] As is understood by a person skilled in the art, although: (1)the cleaned reactor chamber 10 as illustrated within the schematiccross-sectional diagram of FIG. 1 is disclosed as equivalent, althoughnot necessarily identical, to the cleaned reactor chamber 10 asillustrated within the schematic cross-sectional diagram of FIG. 4; and(2) it is typical and preferred within the present invention that thecleaned plasma reactor chamber 10 as illustrated within the schematiccross-sectional diagram of FIG. 1 be formed employing the plasmastripping method as employed for forming the cleaned reactor chamber 10as illustrated within the schematic cross-sectional diagram of FIG. 4from the supplementally seasoned plasma reactor chamber 10″ asillustrated within the schematic cross-sectional diagram of FIG. 3, wheninitiating the method of the present invention, the cleaned reactorchamber 10 as illustrated within the schematic cross-sectional diagramof FIG. 1 may initially be formed employing alternative methods toassure its cleanliness, including but not limited to other plasmastripping methods and plasma conditioning methods.

[0056] Similarly, as is understood by a person skilled in the art,although the present invention is disclosed within the context of amulti-cycle seasoning/etching/cleaning method for reproducibly andcontrollably forming a series of etched silicon layers with desirableproperties over a series of substrates employed within a microelectronicfabrication, the method of the present invention may alternativelyequivalently be disclosed and claimed as a multi-cyclecleaning/seasoning/etching method, or alternatively to a lesser extentas a multi-cycle etching/cleaning/seasoning method, for forming anidentical series of etched silicon layers with the desirable propertiesover an identical series of substrates, since the present inventionprovides a multi-cycle method where the particular starting point fordescribing the method may be arbitrarily chosen.

[0057] Finally, as is understood by a person skilled in the art, thepreferred embodiment of the present invention is illustrative of thepresent invention rather than limiting of the present invention.Revisions and modifications may be made to methods, materials,structures and dimensions through which is provided an etched siliconlayer within a microelectronic fabrication in accord with the preferredembodiment of the present invention, while still providing an etchedsilicon layer within a microelectronic fabrication in accord with thepresent invention, in accord with the accompanying claims.

What is claimed is:
 1. A method for forming an etched silicon layercomprising: providing a first substrate having formed thereover a firstsilicon layer; etching the first silicon layer to form an etched firstsilicon layer while employing a plasma etch method employing a plasmareactor chamber in conjunction with a plasma etchant gas compositionwhich upon plasma activation provides at least one of an active brominecontaining etchant species and an active chlorine containing etchantspecies, wherein within the plasma etch method: (1) a cleaned plasmareactor chamber is seasoned to provide a seasoned plasma reactor chamberhaving a seasoning polymer layer formed therein; (2) the first siliconlayer is etched to form the etched first silicon layer within theseasoned plasma reactor chamber; and (3) the seasoning polymer layer iscleaned from the seasoned plasma reactor chamber to provide the cleanedplasma reactor chamber after etching the first silicon layer to form theetched first silicon layer within the seasoned plasma reactor chamber,prior to etching a second silicon layer to form an etched second siliconlayer formed over a second substrate within the plasma reactor chamberwhile employing the plasma etch method in accord with (1), (2) and (3).2. The method of claim 1 wherein the substrate is employed within amicroelectronic fabrication selected from the group consisting ofintegrated circuit microelectronic fabrications, ceramic substratemicroelectronic fabrications, solar cell optoelectronic microelectronicfabrications, sensor image array optoelectronic microelectronicfabrications and display image array optoelectronic microelectronicfabrications.
 3. The method of claim 1 wherein the silicon layer isselected from the group consisting of monocrystalline silicon layers,polycrystalline silicon layer and amorphous silicon layers.
 4. Themethod of claim 1 wherein: the silicon layer is masked with a masklayer; and the mask layer is selected from the group consisting ofsilicon containing dielectric hard mask layers and photoresist masklayers.
 5. The method of claim 1 wherein the seasoning polymer layer isformed of a material selected from the group consisting of: silicon andbromine containing seasoning polymer materials; silicon, bromine andoxygen containing seasoning polymer materials; silicon and chlorinecontaining seasoning polymer materials; silicon, chlorine and oxygencontaining seasoning polymer materials; silicon, bromine and chlorinecontaining seasoning polymer materials; and silicon, bromine, chlorineand oxygen containing seasoning polymer materials.
 6. The method ofclaim 1 wherein the seasoning method is selected from the groupconsisting of dummy wafer seasoning methods, product wafer in-situseasoning methods and waferless seasoning methods.
 7. A method forforming an etched monocrystalline silicon layer comprising: providing afirst substrate having formed thereover a first monocrystalline siliconlayer; etching the first monocrystalline silicon layer to form an etchedfirst monocrystalline silicon layer while employing a plasma etch methodemploying a plasma reactor chamber in conjunction with a plasma etchantgas composition which upon plasma activation provides at least one of anactive bromine containing etchant species and an active chlorinecontaining etchant species, wherein within the plasma etch method: (1) acleaned plasma reactor chamber is seasoned to provide a seasoned plasmareactor chamber having a seasoning polymer layer formed therein; (2) thefirst monocrystalline silicon layer is etched to form the etched firstmonocrystalline silicon layer within the seasoned plasma reactorchamber; and (3) the seasoning polymer layer is cleaned from theseasoned plasma reactor chamber to provide the cleaned plasma reactorchamber after etching the first monocrystalline silicon layer to formthe etched first monocrystalline silicon layer within the seasonedplasma reactor chamber, prior to etching a second monocrystallinesilicon layer to form an etched second monocrystalline silicon layerformed over a second substrate within the plasma reactor chamber whileemploying the plasma etch method in accord with (1), (2) and (3).
 8. Themethod of claim 7 wherein the substrate is employed within amicroelectronic fabrication selected from the group consisting ofintegrated circuit microelectronic fabrications, ceramic substratemicroelectronic fabrications, solar cell optoelectronic microelectronicfabrications, sensor image array optoelectronic microelectronicfabrications and display image array optoelectronic microelectronicfabrications.
 9. The method of claim 7 wherein: the firstmonocrystalline silicon layer is masked with a mask layer; and the masklayer is selected from the group consisting of silicon containingdielectric hard mask layers and photoresist mask layers.
 10. The methodof claim 7 wherein the seasoning polymer layer is formed of a materialselected from the group consisting of: silicon and bromine containingseasoning polymer materials; silicon, bromine and oxygen containingseasoning polymer materials; silicon and chlorine containing seasoningpolymer materials; silicon, chlorine and oxygen containing seasoningpolymer materials; silicon, bromine and chlorine containing seasoningpolymer materials; and silicon, bromine, chlorine and oxygen containingseasoning polymer materials.
 11. The method of claim 7 wherein theseasoning method is selected from the group consisting of dummy waferseasoning methods, product wafer in-situ seasoning methods and waferlessseasoning methods.
 12. A method for forming an etched polycrystallinesilicon layer comprising: providing a first substrate having formedthereover a first polycrystalline silicon layer; etching the firstpolycrystalline silicon layer to form an etched first polycrystallinesilicon layer while employing a plasma etch method employing a plasmareactor chamber in conjunction with a plasma etchant gas compositionwhich upon plasma activation provides an active bromine containingetchant species, wherein within the plasma etch method: (1) a cleanedplasma reactor chamber is seasoned to provide a seasoned plasma reactorchamber having a seasoning polymer layer formed therein; (2) the firstpolycrystalline silicon layer is etched to form the etched firstpolycrystalline silicon layer within the seasoned plasma reactorchamber; and (3) the seasoning polymer layer is cleaned from theseasoned plasma reactor chamber to provide the cleaned plasma reactorchamber after etching the first polycrystalline silicon layer to formthe etched first polycrystalline silicon layer within the seasonedplasma reactor chamber, prior to etching a second polycrystallinesilicon layer to form an etched second polycrystalline silicon layerformed over a second substrate within the plasma reactor chamber whileemploying the plasma etch method in accord with (1), (2) and (3). 13.The method of claim 12 wherein the substrate is employed within amicroelectronic fabrication selected from the group consisting ofintegrated circuit microelectronic fabrications, ceramic substratemicroelectronic fabrications, solar cell optoelectronic microelectronicfabrications, sensor image array optoelectronic microelectronicfabrications and display image array optoelectronic microelectronicfabrications.
 14. The method of claim 12 wherein: the polycrystallinesilicon layer is masked with a mask layer; and the mask layer isselected from the group consisting of silicon containing dielectric hardmask layers and photoresist mask layers.
 15. The method of claim 12wherein the seasoning polymer layer is formed of a material selectedfrom the group consisting of silicon and bromine containing seasoningpolymer materials; silicon, bromine and oxygen containing seasoningpolymer materials; silicon and chlorine containing seasoning polymermaterials; silicon, chlorine and oxygen containing seasoning polymermaterials; silicon, bromine and chlorine containing seasoning polymermaterials; and silicon, bromine, chlorine and oxygen containingseasoning polymer materials.
 16. The method of claim 12 wherein theseasoning method is selected from the group consisting of dummy waferseasoning methods, product wafer in-situ seasoning methods and waferlessseasoning methods.